Hello Sir,
I have made the Boost PFC pre regulator in which i had a problem with the transformer design . i had used E42/21/15 core as per my Area Product . i had 30 no of turns in primary winding and in auxillary winding 4 turns in transformer. the problem is that auxillary output which is require 17V for UC3854 is not coming actually it is in between 0 to 1 V. please help me regarding this.
another thing there is 30Kohm resistor in design of 250W Preregulator design which is in UC 3854 Appnote (U-134) As well as in datasheet. i cant understand the function of this 30K resistor.
please help me